In September, film director James Cameron contacted The New York Times, disgruntled by a declaration made by millionaire adventurer Victor Vescovo, that claimed he had completed the deepest submarine dive in history.

Vescovo had dived down to the Mariana Trench, off the coast of Guam — the same area Cameron had dived down to seven years earlier.

What irked Cameron was that the area is flat, according to what he and another expedition both saw, meaning it should have been impossible to go any deeper.

Yet Vescovo was claiming he’d gone 52 feet deeper. He also told Business Insider he’d be returning in 2020 to hopefully settle the dispute, once and for all.

Academy Award winning director James Cameron does not seem to like to be upstaged.

In September, Cameron took issue when fellow millionaire adventurer Victor Vescovo declared he had completed the deepest submarine dive in history.

The dive was down to a trough called Challenger Deep, which Cameron also dove down to seven years earlier. Cameron questioned Vescovo’s claim since he and earlier divers had found the area to be flat. He argued that this meant it should have been impossible to go any deeper. Yet Vescovo claimed he’d gone 52 feet further.

What followed, as the two wealthy men disagreed via the headlines of international media companies, is a little unusual.

Here’s what happened.

Why James Cameron is arguing with a fellow millionaire about who dove to the deepest point in the ocean slides

Why James Cameron is arguing with a fellow millionaire about who dove to the deepest point in the ocean slides

This strange argument between two wealthy "gentleman explorers" began when Cameron emailed The New York Times with the subject "Request to Speak."

Challenger Deep is a trough on the Mariana trench, which is the deepest part of the world's oceans, located in the western Pacific off the coast of Guam.

Cameron wasn't the first to reach it. That was achieved in 1960, by Don Walsh and Jacques Piccard, two men in the US Navy. The pair spent 20 minutes down below, but couldn't take any photos, as their submarine stirred up too much of the seafloor.

What set Cameron on fire is that Vescovo said he descended 35,853 feet, which is 52 feet deeper than Cameron went in 2012.

But Cameron said he couldn't have gone deeper, because the bottom was "flat and featureless." So even if Vescovo's gauge was different from Cameron's, the director said it wasn't correct. "I question that result," he told Wired. "I also question why nobody else has questioned that result."

In September, Vescovo's figure was lowered by 13 feet, to 35,840 feet. This still has Vescovo as having gone deeper.

Vescovo's crew also estimated the margin of error for his dive could be up to 70 feet.

Vescovo said the difference of 50 feet was "splitting hairs" when the real focus should have been about the fact they'd both descended down over 35,000 feet. But that's easy for Vescovo to say, when he's the one who's recorded going deeper.

And it clearly matters to Cameron. He told Popular Science, "At the risk of sounding like sour grapes, it's important for the public to know that the one deepest point in our world’s oceans is a flat, featureless plain."

Regardless of who went deeper, as Mark Zumberge, a geophysicist at the Scripps Institution of Oceanography, told Popular Science, the answer isn't a big deal for everyone. "There's not a great scientific interest in how the ocean floor varies in a few meters," he said.